Chválová Katerina, Brabec Viktor, Kaspárková Jana
Institute of Biophysics, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
Nucleic Acids Res. 2007;35(6):1812-21. doi: 10.1093/nar/gkm032. Epub 2007 Feb 28.
DNA-protein cross-links are formed by various DNA-damaging agents including antitumor platinum drugs. The natures of these ternary DNA-Pt-protein complexes (DPCLs) can be inferred, yet much remains to be learned about their structures and mechanisms of formation. We investigated the origin of these DPCLs and their cellular processing on molecular level using gel electrophoresis shift assay. We show that in cell-free media cisplatin [cis-diamminedichloridoplatinum(II)] forms DPCLs more effectively than ineffective transplatin [trans-diamminedichloridoplatinum(II)]. Mechanisms of transformation of individual types of plain DNA adducts of the platinum complexes into the DPCLs in the presence of several DNA-binding proteins have been also investigated. The DPCLs are formed by the transformation of DNA monofunctional and intrastrand cross-links of cisplatin. In contrast, interstrand cross-links of cisplatin and monofunctional adducts of transplatin are stable in presence of the proteins. The DPCLs formed by cisplatin inhibit DNA polymerization or removal of these ternary lesions from DNA by nucleotide excision repair system more effectively than plain DNA intrastrand or monofunctional adducts. Thus, the bulky DNA-protein cross-links formed by cisplatin represent a more distinct and persisting structural motif recognized by the components of downstream cellular systems processing DNA damage considerably differently than the plain DNA adducts of this metallodrug.
DNA-蛋白质交联是由包括抗肿瘤铂类药物在内的多种DNA损伤剂形成的。这些三元DNA-铂-蛋白质复合物（DPCLs）的性质可以推断出来，但关于它们的结构和形成机制仍有许多有待了解之处。我们使用凝胶电泳迁移率变动分析在分子水平上研究了这些DPCLs的起源及其细胞处理过程。我们发现，在无细胞培养基中，顺铂[顺-二氨二氯铂（II）]比无效的反铂[反-二氨二氯铂（II）]更有效地形成DPCLs。我们还研究了在几种DNA结合蛋白存在的情况下，铂配合物的各种类型的普通DNA加合物转化为DPCLs的机制。DPCLs是由顺铂的DNA单功能和链内交联的转化形成的。相比之下，顺铂的链间交联和反铂的单功能加合物在蛋白质存在下是稳定的。顺铂形成的DPCLs比普通的DNA链内或单功能加合物更有效地抑制DNA聚合或通过核苷酸切除修复系统从DNA中去除这些三元损伤。因此，顺铂形成的大分子DNA-蛋白质交联代表了一种更独特和持久的结构基序，与这种金属药物的普通DNA加合物相比，下游处理DNA损伤的细胞系统成分对其识别方式有很大不同。
